Combination Chemotherapy and Rituximab in Treating Patients With Newly Diagnosed Primary CNS Lymphoma

OBJECTIVES: Primary * Determine the rate of toxicity, in terms of percentage of patients with grade 4 neurotoxicity, in patients with untreated primary CNS lymphoma treated with induction therapy comprising high-dose methotrexate, leucovorin calcium, rituximab, and temozolomide followed by consolidation therapy comprising cytarabine and etoposide phosphate. Secondary * Determine the efficacy of this regimen, in terms of the 4-month and 12-month complete and best response rate, in these patients. * Determine the progression-free and overall survival of patients treated with this regimen. * Determine the percentage of patients experiencing toxicity or neurotoxicity due to this regimen. * Determine the treatment-related mortality rate in patients treated with this regimen. * Document the neurocognitive changes in these patients using the Mini-Mental Status Examination during the first year of treatment with this regimen. OUTLINE: This is a pilot, multicenter study. * Induction therapy: Patients receive high-dose methotrexate IV over 4 hours on days 1,15, 29, 43, 57, 71, and 99; leucovorin calcium IV every 6 hours on days 2-4, 16-18, 30-32, 44-46, 58-60, 72-74, and 100-102; oral temozolomide on days 7-11, 35-39, 63-67, 91-95, and 119-123; and rituximab IV on days 3, 17, 31, 45, 59, and 74. Treatment continues in the absence of disease progression or unacceptable toxicity. Patients who achieve complete response proceed to consolidation therapy. * Consolidation therapy I: Beginning 3-4 weeks after completing induction therapy, patients receive high-dose methotrexate IV over 4 hours on day 1, leucovorin calcium IV every 6 hours on days 2-4, and oral temozolomide on days 7-11. * Consolidation therapy II: Beginning 3-5 weeks after completing consolidation therapy I, patients receive cytarabine IV over 2 hours twice daily and etoposide phosphate IV continuously on days 1-4 and filgrastim (G-CSF) subcutaneously beginning on day 14 and continuing until blood counts recover. After completion of study treatment, patients are followed periodically for 2 years. PROJECTED ACCRUAL: A total of 10 patients will be accrued to this study.